常德鲜湿米粉发酵过程中的菌群变化

Changes of Main Microflora in Changde Fresh Wet Rice Noodles

摘要:

为探讨常德鲜湿米粉发酵过程中的菌群变化，本文对常德鲜湿米粉发酵过程中主要微生物的种类、组成变化及致病菌的安全威胁进行了研究。结果表明，自然发酵过程中的优势菌为乳酸菌和酵母菌。发酵液的pH值随着发酵的进行从最初的6.21不断降低，在发酵到8~12 h时达3.69后稍有回升，发酵结束后回升到4.20。大米的蛋白质、粗脂肪和灰分含量在发酵后分别降低了24.92%、31.01%、81.37%，而总淀粉含量在发酵前后无显著性变化。蜡样芽孢杆菌的注入对于发酵液的pH值变化无显著影响。发酵液中蜡样芽孢杆菌在103 cfu/g水平时，随着发酵的进行其数量会逐步减少，带来的安全风险可控。但是当达到104 cfu/g水平时，尽管发酵后蜡样芽孢杆菌数量有所下降，但是浓度仍在较高水平，对米粉制品安全性存在威胁。

Abstract:

To explore the changes of microflora in the natural fermentation process of Changde fresh wet rice noodles, the main microbial species, variation and pathogen threats were studied. The results showed that the lactobacillus and yeast were dominant bacteria during the natural fermentation. The pH of fermentation broth was decreased from 6.21 to 3.69 after 8~12 h fermentation, and then increased slightly to 4.20 at the ends of fermentation. Compared with unfermented rice, the contents of proteins, crude fat and ash in fermented rice were significantly decreased by 24.92%, 31.01%, and 81.37%, respectively. The starch content had no obvious change. The injection of Bacillus cereus presented less effect to pH of the fermentation broth. The risk of Bacillus cereus at 103cfu/g level in fermentation broth was controllable for its number was gradually reduced with fermentation forward. However, when it reached 104 cfu/g, Changde fresh wet rice noodles had a security risk, although its number was decreased after fermentation.